Linear Algebra Examples

$[\begin{array}{c} 5 x & - 4 y \\ 6 x & - 5 y \end{array}]$

Step 1

The inverse of a $2 \times 2$ matrix can be found using the formula $\frac{1}{a d - b c} [\begin{array}{c} d & - b \\ - c & a \end{array}]$ where $a d - b c$ is the determinant.

Step 2

Find the determinant.

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Step 2.1

The determinant of a $2 \times 2$ matrix can be found using the formula $| \begin{array}{c} a & b \\ c & d \end{array} | = a d - c b$ .

$5 x (- 5 y) - 6 x (- 4 y)$

Step 2.2

Simplify the determinant.

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Step 2.2.1

Simplify each term.

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Step 2.2.1.1

Rewrite using the commutative property of multiplication.

$5 \cdot - 5 x y - 6 x (- 4 y)$

Step 2.2.1.2

Multiply $5$ by $- 5$ .

$- 25 x y - 6 x (- 4 y)$

Step 2.2.1.3

Rewrite using the commutative property of multiplication.

$- 25 x y - 6 \cdot - 4 x y$

Step 2.2.1.4

Multiply $- 6$ by $- 4$ .

$- 25 x y + 24 x y$

Step 2.2.2

Add $- 25 x y$ and $24 x y$ .

$- x y$

Step 3

Since the determinant is non-zero, the inverse exists.

Step 4

Substitute the known values into the formula for the inverse.

$\frac{1}{- x y} [\begin{array}{c} - 5 y & 4 y \\ - 6 x & 5 x \end{array}]$

Step 5

Cancel the common factor of $1$ and $- 1$ .

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Step 5.1

Rewrite $1$ as $- 1 (- 1)$ .

$\frac{- 1 (- 1)}{- x y} [\begin{array}{c} - 5 y & 4 y \\ - 6 x & 5 x \end{array}]$

Step 5.2

Move the negative in front of the fraction.

$- \frac{1}{x y} [\begin{array}{c} - 5 y & 4 y \\ - 6 x & 5 x \end{array}]$

Step 6

Multiply $- \frac{1}{x y}$ by each element of the matrix.

$[\begin{array}{c} - \frac{1}{x y} (- 5 y) & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7

Simplify each element in the matrix.

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Step 7.1

Cancel the common factor of $y$ .

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Step 7.1.1

Move the leading negative in $- \frac{1}{x y}$ into the numerator.

$[\begin{array}{c} \frac{- 1}{x y} (- 5 y) & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.1.2

Factor $y$ out of $x y$ .

$[\begin{array}{c} \frac{- 1}{y x} (- 5 y) & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.1.3

Factor $y$ out of $- 5 y$ .

$[\begin{array}{c} \frac{- 1}{y x} (y \cdot - 5) & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.1.4

Cancel the common factor.

$[\begin{array}{c} \frac{- 1}{y x} (y \cdot - 5) & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.1.5

Rewrite the expression.

$[\begin{array}{c} \frac{- 1}{x} \cdot - 5 & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.2

Combine $\frac{- 1}{x}$ and $- 5$ .

$[\begin{array}{c} \frac{- - 5}{x} & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.3

Multiply $- 1$ by $- 5$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.4

Cancel the common factor of $y$ .

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Step 7.4.1

Move the leading negative in $- \frac{1}{x y}$ into the numerator.

$[\begin{array}{c} \frac{5}{x} & \frac{- 1}{x y} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.4.2

Factor $y$ out of $x y$ .

$[\begin{array}{c} \frac{5}{x} & \frac{- 1}{y x} (4 y) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.4.3

Factor $y$ out of $4 y$ .

$[\begin{array}{c} \frac{5}{x} & \frac{- 1}{y x} (y \cdot 4) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.4.4

Cancel the common factor.

$[\begin{array}{c} \frac{5}{x} & \frac{- 1}{y x} (y \cdot 4) \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.4.5

Rewrite the expression.

$[\begin{array}{c} \frac{5}{x} & \frac{- 1}{x} \cdot 4 \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.5

Combine $\frac{- 1}{x}$ and $4$ .

$[\begin{array}{c} \frac{5}{x} & \frac{- 1 \cdot 4}{x} \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.6

Multiply $- 1$ by $4$ .

$[\begin{array}{c} \frac{5}{x} & \frac{- 4}{x} \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.7

Move the negative in front of the fraction.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ - \frac{1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.8

Cancel the common factor of $x$ .

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Step 7.8.1

Move the leading negative in $- \frac{1}{x y}$ into the numerator.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{- 1}{x y} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.8.2

Factor $x$ out of $x y$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{- 1}{x (y)} (- 6 x) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.8.3

Factor $x$ out of $- 6 x$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{- 1}{x (y)} (x \cdot - 6) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.8.4

Cancel the common factor.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{- 1}{x y} (x \cdot - 6) & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.8.5

Rewrite the expression.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{- 1}{y} \cdot - 6 & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.9

Combine $\frac{- 1}{y}$ and $- 6$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{- - 6}{y} & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.10

Multiply $- 1$ by $- 6$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & - \frac{1}{x y} (5 x) \end{array}]$

Step 7.11

Cancel the common factor of $x$ .

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Step 7.11.1

Move the leading negative in $- \frac{1}{x y}$ into the numerator.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 1}{x y} (5 x) \end{array}]$

Step 7.11.2

Factor $x$ out of $x y$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 1}{x (y)} (5 x) \end{array}]$

Step 7.11.3

Factor $x$ out of $5 x$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 1}{x (y)} (x \cdot 5) \end{array}]$

Step 7.11.4

Cancel the common factor.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 1}{x y} (x \cdot 5) \end{array}]$

Step 7.11.5

Rewrite the expression.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 1}{y} \cdot 5 \end{array}]$

Step 7.12

Combine $\frac{- 1}{y}$ and $5$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 1 \cdot 5}{y} \end{array}]$

Step 7.13

Multiply $- 1$ by $5$ .

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & \frac{- 5}{y} \end{array}]$

Step 7.14

Move the negative in front of the fraction.

$[\begin{array}{c} \frac{5}{x} & - \frac{4}{x} \\ \frac{6}{y} & - \frac{5}{y} \end{array}]$